Xbox One sold 23,562 units during its Japanese launch week, less than half the amount sold by Xbox 360.
Microsoft's new machine had four days to reach that total, Famitsu reported. Xbox 360 managed 62,135 units in half the time back in 2005.
The Xbox One's launch was the lowest for any home console in recent years - well below the Wii U (308k in two days), the PlayStation 4 (322k in two days) and any other machine from the last few console generations.
The original Xbox managed 123k in three days back in 2002.
22,416 copies of Titanfall were sold over the Xbox One's launch period - the vast majority being copies of the game bundled with the console.
Rare's Kinect Sports Rivals was the second-best selling game (14,919 copies, again included in a bundle option). Dead Rising 3 was third with 7330 copies sold.
29 titles are now available for the console, representing the vast majority of 2014's biggest games to date along with those available last year at the console's initial North American and European launch.
Other games available on Xbox One include Metal Gear Solid: Ground Zeroes, Call of Duty: Ghosts, Thief, Tomb Raider and Assassin's Creed 4: Black Flag.
Forza Horizon 2, Sunset Overdrive and Halo: The Master Chief Collection are all set to arrive for Japan in time for Christmas.
Xbox has always struggled to make an impression in Japan, which has, traditionally, favoured other consoles. But in recent years all home consoles have struggled as the market shifts its focus to mobile gaming.
Eurogamer investigated why Xbox failed in Japan in a feature published in 2012.